CN109354641B - Process for preparing branched polymers, branched polymers and use of the polymers - Google Patents

Abstract

The present invention provides a process for preparing branched polymers comprising (C ═ C) -CO groups. The method comprises the following steps: (i) providing in the mixture at least one monofunctional monomer comprising one polymerizable carbon-carbon double bond per monomer, at least one multifunctional monomer comprising at least two polymerizable carbon-carbon double bonds per monomer, at least one chain transfer agent comprising a carbonyl group; (ii) forming a polymer from the mixture; and (iii) hydrolyzing the polymer. The invention also provides a branched polymer.

Description

Process for preparing branched polymers, branched polymers and use of the polymers

The present application is a divisional application of the following applications: application date: 2015, 3 months and 27 days; application No.: 201580012806.5, respectively; the invention relates to a method for producing a branched polymer, a branched polymer and the use of said polymer.

Technical Field

The present invention relates to a process for preparing a branched polymer, a branched polymer and the use of said branched polymer, for example as a primary suspending agent in the suspension polymerization of an alkenyl monomer such as vinyl chloride.

Background

Suspension polymerization of monomers such as vinyl chloride typically uses a primary suspending agent. Such primary suspending agents generally help to control the size of the polymer particles and help to inhibit coagulation of the polymer particles. It is sometimes desirable to be able to produce small polymer particles, but some known primary suspending agents are disadvantageous for producing small polymer particles. In the present application, the term "particles" is to be understood in its broadest sense, including non-aggregated particles and particles generated from aggregates of polymerized monomer droplets, commonly known in the art as "particles".

Polymers containing carbonyl groups conjugated with carbon-carbon double bonds are known (e.g.

B72, Synthamer (SYNTHOMER) (uk) limited) and some were used as primary suspending agents. However, some carbonyl-containing polymers are yellow in color, which may be unacceptable to some users.

The present invention seeks to mitigate one or more of the above-mentioned problems. Alternatively or additionally, the present invention seeks to provide an alternative and/or improved primary suspending agent.

Disclosure of Invention

According to a first aspect of the present invention there is provided a free radical polymerisation process for the preparation of a branched polymer comprising (C ═ C) -CO groups, the process comprising:

(i) providing in mixture at least one monofunctional monomer comprising one polymerizable carbon-carbon double bond per monomer, at least one multifunctional monomer comprising at least two polymerizable carbon-carbon double bonds per monomer, at least one chain transfer agent comprising an aldehyde or ketone, and optionally at least one polymerization initiator; and

(ii) forming a polymer from the mixture;

(iii) hydrolyzing the polymer, thereby forming a hydrolyzed polymer.

The (C ═ C) -CO groups are typically formed by hydrolysis of appropriately modified poly (alkenyl alkanoate); it does not require post-hydrolysis treatment, such as heating, to produce the (C ═ C) -CO structure. The (C ═ C) -CO groups are formed at the chain ends by means of the use of chain transfer agents containing carbonyl groups.

For the avoidance of doubt, the process of the present invention is a free radical polymerisation. The free radicals may be generated using any means known to those skilled in the art, such as one or more of the following: polymerization initiators, redox chemicals, and exposure to electromagnetic radiation of an appropriate wavelength (e.g., ultraviolet radiation).

One skilled in the art will recognize that the step of hydrolyzing the polymer does not necessarily result in a 100% hydrolyzed polymer.

For the avoidance of doubt, the above steps (i), (ii) and (iii) need not necessarily be separate and sequential steps. For example, the process of the present invention may comprise first providing at least one monofunctional monomer, at least one multifunctional monomer and at least one polymerization initiator in a mixture, followed by the addition of at least a chain transfer agent comprising an aldehyde or ketone. Polymerization will occur in the absence of chain transfer agents, but upon addition of at least one chain transfer agent, there will be a mixture comprising at least one monofunctional monomer, at least one multifunctional monomer, at least one chain transfer agent, and at least one initiator from which the polymer is formed.

The at least one chain transfer agent comprising an aldehyde or ketone may comprise from 1 to 20 carbon atoms, alternatively from 1 to 10 carbon atoms, alternatively from 2 to 6 carbon atoms, and alternatively from 2 to 4 carbon atoms. For example, at least one (optionally each) of the chain transfer agents may comprise acetaldehyde, propionaldehyde (commonly known as propionaldehyde), butyraldehyde (commonly known as butyraldehyde), isobutyraldehyde, valeraldehyde, caproaldehyde, isovaleraldehyde, 5-chlorovaleraldehyde, 5-dimethyl-1, 3-cyclohexanedione (also known as dimedone), cyclohexanecarboxaldehyde, 3-methylcyclohexanecarboxaldehyde, 3-dibromocyclopentanecarboxaldehyde, trans-2-methylcyclopentanealdehyde, benzaldehyde, substituted benzaldehydes, crotonaldehyde, paraldehyde, chloral, glutaraldehyde, succinaldehyde, 4-hydroxy-3-methylbutylaldehyde, or acetone, butan-2-one (commonly known as methylethylketone or MEK), methylpropylketone, butyraldehyde, or a mixture thereof, Methyl isopropyl ketone, methyl isobutyl ketone, ethyl propyl ketone, diethyl ketone, acetophenone, cyclohexanone, acetylacetone, benzophenone, or oxopentanal (oxypentanal), 3, 4-dioxopentanal, 3-methyl-3-oxo-butyraldehyde, butane-2, 3-dione, 2, 4-pentanedione, 2, 3-hexanedione, cyclopentanone, 2-bromocyclopentanone, 4-hydroxycyclohexanone, 2-bromo-5-methylcyclohexanone, 1, 4-cyclohexanedione, 1, 2-cyclopentanedione, 4-hydroxy-2-butanone, 1, 5-dihydroxy-3-pentanone, 4-penten-2-one, trans-3-pentanal, (E) -3-methyl-3-pentenal, (Z) -5-bromo-4-hexen-3-one, benzoin, furfural or substituted furfural and the like.

The method may include providing more than one chain transfer agent. For example, the method can include providing a first chain transfer agent and a second chain transfer agent comprising a carbonyl group, such as an aldehyde or ketone. The second chain transfer agent may optionally comprise an aldehyde or a ketone, or the second chain transfer agent may optionally comprise no aldehyde or ketone.

The amount of the chain transfer agent comprising the aldehyde or ketone may be 0.005% to 50 mol% of the amount of the monofunctional monomer, that is, the number of moles of the chain transfer agent comprising the aldehyde or ketone may be selectively 0.005 to 50% of the number of moles of the monofunctional monomer. This should be calculated using the total amount of chain transfer agent comprising aldehyde or ketone and the total amount of monofunctional monomer, even if more than one monofunctional monomer and/or more than one chain transfer agent comprising aldehyde or ketone is used.

The amount of chain transfer agent comprising an aldehyde or ketone can optionally be at least 0.005 mol%, at least 0.05 mol%, at least 0.5 mol%, at least 1 mol%, at least 5 mol%, at least 7 mol%, at least 10 mol%, no greater than 20 mol%, no greater than 25 mol%, no greater than 30 mol%, no greater than 40 mol%, no greater than 45 mol%, and optionally no greater than 50 mol% of the amount of monofunctional monomer, based on the total amount of chain transfer agent comprising an aldehyde or ketone and the total amount of monofunctional monomer. Alternatively, the amount of chain transfer agent comprising an aldehyde or ketone can be selectively 0.5 to 50 mol%, 0.5 to 45 mol%, 0.5 to 30 mol%, 1 to 25 mol%, 5 to 45 mol%, 5 to 25 mol%, 7 to 40 mol%, 10 to 25 mol%, and optionally 10 to 20 mol% of the amount of monofunctional monomer, based on the total amount of chain transfer agent comprising an aldehyde or ketone and the total amount of monofunctional monomer. The amount of the chain transfer agent may, for example, depend on the nature of the solvent used. For example, certain solvents have relatively high chain transfer constants for the polymerization reaction in question, and therefore, it may not be necessary to use large amounts of the chain transfer agent to inhibit gel formation. For example, because isopropanol has a relatively high chain transfer constant for the polymerization of vinyl acetate, when the monofunctional monomer is vinyl acetate, a solvent containing a relatively high isopropanol content reduces the amount of chain transfer agent needed to inhibit gel formation. However, those skilled in the art will recognize that incorporation of a solvent residue into the polymer, rather than a chain transfer agent residue, may be undesirable from the standpoint of incorporating into the polymer the desired carbonyl functionality associated with the chain transfer agent residue from the aldehyde or ketone. One skilled in the art will recognize that solvents with very low chain transfer constants may be used.

The ratio of the number of moles of chain transfer agent comprising aldehyde or ketone to the number of moles of multifunctional monomer based on the total amount of chain transfer agent comprising aldehyde or ketone and the total amount of multifunctional monomer may be at least 10: 1. at least 20: 1. at least 30: 1. at least 50: 1. at least 70: 1. at least 100: 1. and at least 120: 1. the ratio of the number of moles of chain transfer agent comprising aldehyde or ketone to the number of moles of multifunctional monomer based on the total amount of chain transfer agent comprising aldehyde or ketone and the total amount of multifunctional monomer may be no greater than 100: 1. not more than 120: 1. not more than 150: 1. not more than 200: 1. and optionally no greater than 300: 1. for example, for solution polymerization, the relative amount of chain transfer agent is generally higher than for suspension polymerization, and thus, the ratio may be, for example, at least 50: 1. optionally at least 70: 1. optionally at least 90: 1. optionally no greater than 150: 1. optionally no greater than 200: 1. and optionally no greater than 300: 1. for example, the ratio of the number of moles of chain transfer agent comprising aldehyde or ketone to the number of moles of multifunctional monomer based on the total amount of chain transfer agent comprising aldehyde or ketone and the total amount of multifunctional monomer may be 30:1 to 200: 1. alternatively 50:1 to 150: 1. and optionally 70: 1 to 120: 1.

for suspension polymerization, the ratio may be lower, for example at least 30: 1. at least 50: 1. optionally no greater than 100: 1. and optionally no greater than 150: 1.

substantially all of the chain transfer agent comprising an aldehyde or ketone may be mixed with one or more of at least one monofunctional monomer, at least one multifunctional monomer, and optionally at least one polymerization initiator (if present) at the beginning of the polymerization reaction. This may be effective, for example, if the amount of multifunctional monomer is relatively low (e.g., no more than 0.1 mol% and optionally no more than 0.05 mol% of the amount of monofunctional monomer), or if the polymerization is a suspension reaction.

Alternatively, the method may include delaying the addition of at least some chain transfer agent comprising an aldehyde or ketone. The method may comprise delaying the addition of at least 50%, optionally at least 60%, optionally at least 70%, optionally at least 80%, optionally at least 90% and optionally substantially all of the chain transfer agent comprising the aldehyde or ketone. Thus, the process may comprise less than 10% (and optionally substantially none) of chain transfer agent comprising an aldehyde or ketone in the reaction mixture at the start of the reaction. The process may provide at least 5%, optionally at least 10%, and optionally at least 15% of a chain transfer agent comprising an aldehyde or ketone, mixed with one or more of at least one monofunctional monomer, at least one multifunctional monomer, and optionally at least one polymerization initiator (if present), prior to the start of the polymerization reaction. The delayed addition of the chain transfer agent may be carried out continuously or discontinuously (e.g., in a series of discrete portions). The process may add at least 50%, optionally at least 60%, and optionally at least 70% of a chain transfer agent comprising an aldehyde or ketone for up to 4 hours, optionally up to 3 hours, optionally up to 2 hours, optionally up to 1 hour after the start of the polymerization reaction. The method may comprise adding at least 50%, optionally at least 60%, optionally at least 70%, optionally at least 80%, optionally at least 90% of a chain transfer agent comprising an aldehyde or ketone when the percent conversion of the monounsaturated monomers is not greater than 70%.

It has been found that it may be advantageous to carry out the delayed addition at relatively short time intervals after the start of the polymerization reaction. The method may comprise adding at least 50%, optionally at least 60%, optionally at least 70%, optionally at least 80%, optionally at least 90% and optionally substantially all of said chain transfer agent comprising an aldehyde or ketone before the percent conversion of the monofunctional monomer reaches 60%, optionally 40%, optionally 30%, and optionally 20%.

Each monofunctional monomer contains one (and only one) polymerizable carbon-carbon double bond per molecule. The carbon-carbon double bond will undergo addition polymerization to form a polymer.

At least one monofunctional monomer may contain other unsaturated groups, such as, for example, a C ═ O double bond.

Each monofunctional monomer may comprise any monomer that can be polymerized by a free radical reaction mechanism. The term monomer also encompasses suitable reactive oligomers (typically comprising less than 5 repeating units), or polymers (typically comprising 5 or more repeating units).

The polymerizable carbon-carbon double bond of the at least one (and optionally each) monofunctional monomer may be in the form of a carbon-carbon double bond of the alkenyl group.

For example, the at least one (and optionally each) monofunctional monomer may comprise from 1 to 20 carbon atoms, but may optionally comprise more than 20 carbon atoms. Alternatively, the monofunctional monomer may comprise from 1 to 10, alternatively from 2 to 8, and alternatively from 3 to 6 carbon atoms.

The molecular weight of the at least one (and optionally each) monofunctional monomer may be, for example, less than 2000g.mol^-1Optionally less than 1500g.mol^-1Alternatively less than 1000g.mol^-1Alternatively less than 500g.mol^-1Optionally less than 200g.mol^-1。

The at least one monofunctional monomer may be, for example, an ester (such as an alkenyl alkanoate (e.g., vinyl acetate)). At least one monofunctional monomer may be optionally substituted. The at least one monofunctional monomer may optionally comprise an optionally substituted alkenyl alkanoate.

As described above, the method may include providing at least one (and, thus, possibly more than one) monofunctional monomer.

Thus, a second monofunctional monomer may be present. One or both of the first and second monofunctional monomers may be, for example, an ester (such as an alkenyl alkanoate (e.g., vinyl propionate), or an alkyl alkanoate (such as methyl acrylate)), an amide (such as acrylamide), an anhydride (such as maleic anhydride), an acid (such as itaconic acid), an imide (e.g., maleimide), or an alkene (e.g., ethylene). The second monofunctional monomer may be optionally substituted. The second monofunctional monomer may optionally comprise an optionally substituted alkenyl alkanoate, or an optionally substituted alkyl alkenoate. The alkenyl alkanoate, if present, optionally contains 3 to 10 carbon atoms, optionally 3 to 6 carbon atoms. The alkyl alkenoate, if present, optionally contains 3 to 10 carbon atoms, optionally 3 to 6 carbon atoms.

Once the polymer is synthesized, the at least one monofunctional monomer may comprise a reactive moiety for subsequent reaction. For example, the at least one monofunctional monomer may comprise one or more ester moieties that can be hydrolyzed to form a hydroxyl or acid group.

The carbon-carbon double bond of the at least one monofunctional monomer may be incorporated into the non-cyclic moiety. Alternatively, the at least one monofunctional monomer may comprise one or more cyclic moieties with carbon-carbon double bonds incorporated into the cyclic moieties, as in maleic anhydride.

Further examples of suitable monofunctional monomers include vinyl methyl acetate, propenyl methyl acetate, propenyl ethyl acetate, butenyl methyl acetate, vinyl propionate, propenyl propionate, vinyl benzoate, vinyl 4-tert-butylbenzoate, vinyl chloroformate, vinyl cinnamate, vinyl decanoate, vinyl neodecanoate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl hexanoate, vinyl heptanoate, vinyl octanoate, vinyl 2-propylheptanoate, vinyl nonanoate, vinyl neononanoate, vinyl stearate, vinyl trifluoroacetate, and vinyl valerate.

Examples of suitable monofunctional monomers include: ethylene, esters of monoethylenically unsaturated C3-C6 monocarboxylic acids having C1-C20 alkanols, cycloalkanols, phenyl-C1-C4 alkanols or phenoxy-C1-C4 alkanols, in particular the aforementioned esters of acrylic acid and the aforementioned esters of methacrylic acid; diesters of monoethylenically unsaturated C4-C6 dicarboxylic acids with C1-C20 alkanols, cycloalkanols, phenyl-C1-C4 alkanols or phenoxy-C1-C4 alkanols, in particular the aforementioned esters of maleic acid and esters of fumaric acid; amides of monoethylenically unsaturated C3-C6-monocarboxylic acids having C4-C20-alkylamines or di-C2-C20-alkylamines; vinyl, allyl, methallyl esters of saturated aliphatic carboxylic acids, especially saturated aliphatic C2-C18 monocarboxylic acids, especially vinyl esters. Examples of esters of monoethylenically unsaturated C3-C6 monocarboxylic acids having C1-C20 alkanols, cycloalkanols, phenyl-C1-C4 alkanols or phenoxy-C1-C4 alkanols are in particular esters of acrylic acid, such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, 2-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, 3-propylheptyl acrylate, decyl acrylate, lauryl acrylate, stearyl acrylate, cyclohexyl acrylate, benzyl acrylate, 2-phenylethyl acrylate, 1-phenylethyl acrylate, 2-phenoxyethyl acrylate, and also esters of methacrylic acid, such as methyl methacrylate, ethyl methacrylate, N-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, 2-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, decyl methacrylate, lauryl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 2-phenylethyl methacrylate, 1-phenylethyl methacrylate and 2-phenoxyethyl methacrylate. Examples of diesters of monoethylenically unsaturated C4-C6 dicarboxylic acids with C1-C20 alkanols, cycloalkanols, phenyl-C1-C4 alkanols or phenoxy-C1-C4 alkanols, in particular diesters of maleic acid and diesters of fumaric acid, more particularly di-C1-C20 alkyl maleic acid esters and di-C1-C20 alkyl fumaric acid esters, such as dimethyl maleate, diethyl maleate, di-n-butyl maleate, dimethyl fumarate, diethyl fumarate and di-n-butyl fumarate. Examples of vinyl, allyl and methallyl esters of saturated aliphatic carboxylic acids include in particular the vinyl esters of C2-C18 monocarboxylic acids, such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate tertiaryhexanoate, vinyl 2-ethylhexanoate, vinyl laurate and vinyl stearate, and also the corresponding allyl and methallyl esters. The monomers also comprise esters of monoethylenically unsaturated C3-C6 monocarboxylic acids, more particularly esters of acrylic or methacrylic acid with C1-C20 alkanols, cycloalkanols, phenyl-C1-C4 alkanols or phenoxy-C1-C4 alkanols, preferably diesters of monoethylenically unsaturated C4-C6 dicarboxylic acids with C1-C20 alkanols, cycloalkanols, phenyl-C1-C4 alkanols or phenoxy-C1-C4 alkanols.

Examples of suitable monofunctional monomers also include esters of monoethylenically unsaturated C3-C6 monocarboxylic acids, more particularly esters of acrylic or methacrylic acid, optionally with C1-C20 alkanols.

Examples of suitable monofunctional monomers also include esters of acrylic acid with C2-C10 alkanols (e.g., C2-C10 alkyl acrylates), and esters of methacrylic acid with C1-C10 alkanols (e.g., C1-C10 alkyl methacrylates) may be preferred.

Examples of suitable monofunctional monomers also include monoethylenically unsaturated C3-C8 monocarboxylic acids, such as acrylic acid, methacrylic acid, 2-butenoic acid, 3-butenoic acid, 2-acryloxyethyl acetate and 2-methacryloxyethyl acetate; monoethylenically unsaturated C4-C8 monocarboxylic acids, such as maleic acid, itaconic acid, and fumaric acid; primary amides of the aforementioned monoethylenically unsaturated C3-C8 monocarboxylic acids, more particularly acrylamide and methacrylamide, cyclic amides of the aforementioned monoethylenically unsaturated C3-C8 monocarboxylic acids with cyclic amines, such as pyrrolidine, piperidine, morpholine or piperazine, more particularly N-acryloylmorpholine or N-methacryloylmorpholine, hydroxyalkyl esters of the aforementioned monoethylenically unsaturated C3-C8 monocarboxylic acids, such as hydroxyethyl acrylate, hydroxyethyl methacrylate, 2-hydroxypropyl acrylate and 3-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate and 3-hydroxypropyl methacrylate, monoesters of the aforementioned monoethylenically unsaturated C3-C8 monocarboxylic acids and C4-C8 dicarboxylic acids having C2-C4 polyalkylene glycols, more particularly esters of these carboxylic acids having polyethylene glycols or having alkyl-polyethylene glycols, the (alkyl) polyethylene glycol group typically has a molecular weight in the range of from 100 to 5000, especially from 100 to 3000; n-vinylamides of aliphatic C1-C10 carboxylic acids, and N-vinyllactams, such as N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone and N-vinylcaprolactam, monoethylenically unsaturated sulfonic acids in which the sulfonic acid group is bound to an aliphatic hydrocarbon group, such as vinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid, 2-methacrylamido-2-methylpropanesulfonic acid, 2-acrylamidoethanesulfonic acid, 2-acryloxyethanesulfonic acid, 2-methacryloxyethanesulfonic acid, 3-acryloxypropanesulfonic acid, 2-ethylhexylaminoethanesulfonic acid and 2-methacryloxypropanesulfonic acid, and salts thereof, monoethylenically unsaturated phosphonic acids, and esters and salts thereof, the phosphonic acid groups in the monoethylenically unsaturated phosphonic acid being linked to aliphatic hydrocarbon radicals, such as vinylphosphonic acid, 2-acrylamido-2-methylpropanephosphonic acid, 2-methacrylamido-2-methylpropanephosphonic acid, 2-acrylamidoethylphosphonic acid, 2-methacrylamidoethylphosphonic acid, 2-acryloyloxyethylphosphonic acid, 2-methacryloyloxyethylphosphonic acid, 3-acryloyloxypropylphosphonic acid and 2-methacryloyloxypropylphosphonic acid and salts thereof, and monoethylenically unsaturated phosphorus monoesters, more particularly monoesters of phosphoric acid having a hydroxy-C2-C4 alkyl acrylate and a hydroxy-C2-C4 alkyl methacrylate, such as, for example, 2-acryloyloxyethyl phosphate, 2-methacryloyloxyethyl phosphate, 3-acryloxypropyl phosphate, 3-methacryloxypropyl phosphate, 4-acryloxybutyl phosphate and 4-methacryloxybutyl phosphate and their salts.

Examples of monofunctional monomers also include monoethylenically unsaturated C3-C8 monocarboxylic acids, more specifically acrylic acid and methacrylic acid, amides of the aforementioned monoethylenically unsaturated C3-C8 monocarboxylic acids, more specifically acrylamide and methacrylamide, and hydroxyalkyl esters of the aforementioned monoethylenically unsaturated C3-C8 monocarboxylic acids, such as hydroxyethyl acrylate, hydroxyethyl methacrylate, 2-hydroxypropyl acrylate and 3-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate and 3-hydroxypropyl methacrylate.

Examples of combinations of monofunctional monomers include vinyl acetate and vinyl propionate, vinyl acetate and itaconic acid, vinyl acetate and di (alkyl) maleate, vinyl acetate and ethylene, or vinyl acetate and methyl (meth) acrylate. The copolymer may be a statistical distribution or a block distribution of monofunctional monomers consisting along the polymer chain.

Each multifunctional monomer may comprise any monomer that is polymerizable by a free radical mechanism. The term "monomer" when used as a monofunctional monomer (or monomers) also includes suitable reactive oligomers (typically containing less than 5 repeating units), or polymers (typically containing 5 or more repeating units).

One or more (and optionally each) of the carbon-carbon double bonds of at least one (and optionally each) multifunctional monomer may be an alkenyl carbon-carbon double bond.

The at least one multifunctional monomer optionally comprises at least two (and optionally at least three) polymerizable carbon-carbon double bonds per molecule.

At least one of the multifunctional monomers may comprise a difunctional monomer, i.e., comprising two, and no more than two, polymerizable C-C double bonds. Examples of suitable difunctional monomers include di (meth) acrylates or diallyl compounds, such as diacrylates and di (meth) acrylates, such as ethylene glycol di (meth) acrylate, hexanediol di (meth) acrylate, tripropylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, and vinyl acrylates, such as allyl (meth) acrylate, butadiene, diallyl succinate, diallyl carbonate, diallyl phthalate, and substituted analogues thereof.

For example, the at least one multifunctional monomer may be a trifunctional monomer, i.e., containing three, and no more than three, polymerizable C-C double bonds.

The trifunctional monomer comprises: tripropylene glycol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, 1, 3, 5-triallyl-1, 3, 5-triazine-2, 4, 6(1H, 3H, 5H) -trione ("TTT"), or diallyl maleate.

The at least one multifunctional monomer may comprise a tetrafunctional monomer comprising four (and only four) polymerizable C-C double bonds. An example of a tetrafunctional monomer is pentaerythritol tetra (meth) acrylate.

At least one multifunctional monomer may comprise a pentafunctional monomer comprising five (and only five) polymerizable C-C double bonds. Examples of pentafunctional monomers include: glucose penta (meth) acrylate.

At least one and preferably each multifunctional monomer is a monomer that does not undergo hydrolysis/transesterification reactions.

The molecular weight of the at least one multifunctional monomer may be, for example, greater than 100g.mol^-1Alternatively greater than 200g.mol^-1Alternatively greater than 300g.mol^-1Alternatively less than 2000g.mol^-1Optionally less than 1500g.mol^-1Alternatively less than 1000g.mol^-1Alternatively less than 500g.mol^-1。

At least one multifunctional monomer may optionally comprise a cyclic moiety to which is attached a group comprising a polymerizable carbon-carbon double bond. Typically, each polymerizable carbon-carbon double bond will, optionally spaced apart, be attached to a different atom of the cyclic moiety from each other. The cyclic moiety may comprise, for example, a five or six membered ring. For example, the ring may comprise a 1, 3, 5-triazine-2, 4, 6-trione moiety or a benzene moiety.

As noted above, the method can include providing more than one multifunctional monomer, each multifunctional monomer comprising more than one polymerizable carbon-carbon double bond. Each multifunctional monomer may comprise the characteristics described above in relation to the multifunctional monomer. The method can include, for example, providing a first multifunctional monomer and a second multifunctional monomer. Examples of suitable combinations include ethylene glycol di (meth) acrylate and butylene glycol di (meth) acrylate, ethylene glycol di (meth) acrylate and diallyl maleate, TTT and diallyl succinate, TTT and diallyl carbonate, TTT and butylene glycol di (meth) acrylate, TTT and ethylene glycol di (meth) acrylate.

The amount of multifunctional monomer can be at least 0.005 mol%, at least 0.05 mol%, at least 0.1 mol%, optionally at least 0.2 mol%, optionally not more than 0.4 mol%, not more than 0.5 mol%, not more than 0.6 mol%, not more than 0.8 mol%, not more than 1 mol%, not more than 2 mol%, and optionally not more than 5 mol% of the monofunctional monomer content (typically based on the total monofunctional monomer content and the total multifunctional monomer content). Alternatively, the amount of multifunctional monomer may be 0.005 to 1 mol%, 0.05 to 0.8 mol%, 0.1 to 0.6 mol%, 0.1 to 0.5 mol%, alternatively 0.1 to 0.4 mol%, and alternatively 0.2 to 0.4 mol% of the monofunctional monomer content (typically based on the total monofunctional monomer content and the total multifunctional monomer content).

The process may comprise carrying out solution polymerization, bulk polymerization or suspension polymerization.

If the polymerization reaction is a solution polymerization reaction, the solvent used in the solution polymerization may comprise a mixture of a first solvent component and a second solvent component, the first solvent component having a first chain transfer constant and the second solvent component having a second chain transfer constant, the second chain transfer constant being greater than the first chain transfer constant, the second chain transfer constant optionally being at least two times greater, optionally at least three times greater, optionally at least four times greater, optionally at least five times greater, and optionally at least six times greater than the first chain transfer constant. This may be particularly useful if it is desired or necessary for the solvent to participate in the chain termination process, for example, to inhibit excessive crosslinking and gelation. Those skilled in the art will recognize that the chain transfer constant will depend on the monofunctional monomer being polymerized. For example, for the polymerization of vinyl monomers, the solvent may comprise methanol and isopropanol, the chain transfer constant of which is about 8 times that of methanol. The second solvent component can comprise at least 1 mol%, at least 3 mol%, at least 5 mol%, at least 8 mol%, at least 10 mol%, and optionally at least 15 mol% of the content of the first solvent component. The second solvent component can comprise no more than 10 mol%, no more than 15 mol%, no more than 20 mol%, no more than 25 mol%, and optionally no more than 30 mol% of the content of the first solvent component.

For example, the polymerization may be carried out using a redox system at atmospheric pressure between 0 ℃ and 25 ℃, more typically at elevated temperature, typically at least 30 ℃, at least 40 ℃, at least 50 ℃, at least 60 ℃, at least 65 ℃, at least 70 ℃, optionally no greater than 100 ℃, no greater than 90 ℃, and optionally no greater than 80 ℃. Those skilled in the art will appreciate that these values may be increased if the reaction is carried out under pressure.

The method may include delaying the addition of at least some of at least one or more of at least one monofunctional monomer, at least one initiator (if present), and at least one multifunctional monomer. The method can include delaying the addition of at least some of the at least one monofunctional monomer, i.e., at the beginning of the reaction, at least some of the monofunctional monomer is not present in the reaction mixture. The method may comprise delayed addition of up to 5%, alternatively up to 10%, alternatively up to 20%, and alternatively up to 50% of monofunctional monomer.

The method may include providing at least one initiator. The initiator is capable of generating free radicals. The initiator may, for example, comprise an azo initiator, such as azobis (isobutyronitrile) (AIBN), azobis (2-methylbutyronitrile) (AIVN), azobis (2, 4-dimethylvaleronitrile), azobis (4-cyanovaleric acid) or a peroxide, such as hydrogen peroxide, tert-butyl hydroperoxide, dilauroyl peroxide, tert-butyl peroxyneodecanoate, dibenzoyl peroxide, cumene peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxydiethylacetate, tert-butyl peroxybenzoate, or a sulfate salt, such as ammonium persulfate, sodium persulfate, potassium persulfate. The initiator may comprise a redox initiator, a photoinitiator, or an oil soluble initiator.

Examples of redox initiators can be found in US2007/0184732, in particular in paragraph [0043 ].

Examples of photoinitiator systems can be found in US8603730, in particular on lines 6 and 7 of the text.

Further examples of initiators, in particular oil-soluble initiators, can also be found in US209/0258953, in particular in paragraphs [0026] to [0028 ].

The process may include, at the start of the reaction, less than 10% (optionally substantially none) of the initiator in the reaction mixture. The method may comprise providing at least 5%, optionally at least 10%, and optionally at least 15% of an initiator in a mixture having at least one monofunctional monomer, at least one multifunctional monomer, and one or more of the chain transfer agents prior to the start of the polymerization reaction. The delayed addition of the initiator may be carried out continuously or discontinuously (e.g., in a series of discrete portions). The method may comprise adding at least 50%, optionally at least 60%, and optionally at least 70% of said initiator after the start of the polymerization reaction over a time interval of up to 4 hours, optionally up to 3 hours, optionally up to 2 hours, and optionally up to 1 hour. The method may comprise adding at least 50%, optionally at least 60%, optionally at least 70%, optionally at least 80%, optionally at least 90% of the initiator when the conversion of the monounsaturated monomer is not greater than 70%.

It has been found that it may be advantageous to carry out the delayed addition within a relatively short time interval after the start of the polymerization reaction. The method may comprise adding at least 50%, optionally at least 60%, optionally at least 70%, optionally at least 80%, optionally at least 90% and optionally substantially all of the initiator before the percent conversion of the monofunctional monomer reaches 60%, optionally 40%, optionally 30%, and optionally 20%.

The process may include having less than 10% (and optionally substantially none) of at least one monofunctional monomer in the reaction mixture at the start of the reaction. The method may comprise providing at least 5%, optionally at least 10%, and optionally at least 15% of at least one monofunctional monomer in a mixture with one or more of an initiator (if present), at least one multifunctional monomer, and the chain transfer agent, prior to the start of the polymerization reaction. The delayed addition of the at least one monofunctional monomer may occur continuously or discontinuously (e.g., in a series of discontinuous portions). The method may comprise adding at least 50%, optionally at least 60%, and optionally at least 70% of the at least one monofunctional monomer at a time interval of up to 4 hours, optionally up to 3 hours, optionally up to 2 hours, and optionally up to 1 hour after the start of the polymerization reaction.

The process may include having less than 10% (and optionally substantially none) of at least one multifunctional monomer in the reaction mixture at the start of the reaction. The method may comprise providing at least 5%, optionally at least 10%, and optionally at least 15% of at least one multifunctional monomer in a mixture having at least one monofunctional monomer, an initiator (if present), and one or more of the chain transfer agents, prior to the start of the polymerization reaction. The delayed addition of the at least one multifunctional monomer may occur continuously or discontinuously (e.g., in a series of discrete portions). The method may comprise adding at least 50%, optionally at least 60%, and optionally at least 70% of the at least one multifunctional monomer at a time interval of up to 4 hours, optionally up to 3 hours, optionally up to 2 hours, and optionally up to 1 hour after the start of the polymerization reaction. The process may comprise adding at least 50%, optionally at least 60%, optionally at least 70%, optionally at least 80%, optionally at least 90% of the multifunctional monomer at a conversion of the monounsaturated monomer of not more than 70%.

It has been found that it may be advantageous to carry out the delayed addition in a relatively short time after the start of the polymerization reaction. The method may comprise adding at least 50%, optionally at least 60%, optionally at least 70%, optionally at least 80%, optionally at least 90% and optionally substantially all of the at least one multifunctional monomer before the percent conversion of the monofunctional monomer reaches 60%, optionally 40%, optionally 30%, and optionally 20%.

The percent conversion of monofunctional monomer may be at least 70%, alternatively at least 80%, and alternatively at least 90%.

The hydrolysis may be carried out by any suitable method known to those skilled in the art and may be controlled to achieve the desired degree of hydrolysis, optionally at least 60 mol%, optionally at least 65 mol%, optionally at least 70 mol%, optionally not more than 98 mol%, optionally not more than 95 mol%, and optionally not more than 90 mol%. Alternatively, the degree of hydrolysis is from 65% to 95 mol%, and alternatively from 70% to 90 mol%.

In the present application, the term "hydrolysis" is understood in its broadest sense and encompasses base-catalyzed hydrolysis, saponification, acid hydrolysis and transesterification. Further references to hydrolysis can be found in "development of Polyvinyl alcohol (Polyvinyl alcohol derivatives)" edited by c.a. finch, (C)1992 John Wiley & Sons Ltd, chapter iii: hydrolysis of Polyvinyl Acetate to Polyvinyl Alcohol (Chapter 3: Hydrolysis of Polyvinyl Acetate to Polyvinyl Alcohol), by f.l. marten; zvanut, pages 57-77.

The polymer formed prior to hydrolysis may comprise a poly (alkenyl alkanoate), such as poly (vinyl acetate). The polymer formed after hydrolysis may comprise poly (alkenyl alcohol) -co- (alkenyl alkanoate), such as poly (vinyl alcohol) -co (vinyl acetate).

According to a second aspect of the present invention there is provided a branched polymer preparable in accordance with the method of the first aspect of the present invention.

According to a third aspect of the present invention there is provided a branched polymer comprising (C ═ C) -C ═ O groups, the polymer comprising residues of:

(i) at least one monofunctional monomer having one polymerizable double bond per molecule;

(ii) at least one multifunctional monomer having at least two polymerizable double bonds per molecule; and

(iii) at least one chain transfer agent comprising an aldehyde or a ketone.

The (C ═ C) -CO groups are formed at the chain ends by using a chain transfer agent containing a carbonyl group.

The polymer optionally comprises one or more of the following residues:

one or more solvent components, one or more initiators, and a second chain transfer agent. The second chain transfer agent may, for example, be used to introduce certain functionalities into the polymer, as described in relation to the process of the first aspect of the invention.

Of course, the polymer may comprise residues of more than one monofunctional monomer and/or more than one multifunctional monomer.

The polymer optionally comprises a plurality of the various components as mentioned above in the process of the first aspect of the invention. For example, the polymer may comprise at least 0.5 mol%, at least 1 mol%, at least 5 mol%, at least 10 mol%, no greater than 20 mol%, no greater than 25 mol%, no greater than 30 mol%, and optionally no greater than 50 mol% of the residue of the chain transfer agent comprising an aldehyde or ketone, based on the total moles of monofunctional monomer residues and the total moles of chain transfer agent residues comprising an aldehyde or ketone.

One skilled in the art will recognize that residues may be post-processed. For example, the polymer may comprise residues of vinyl acetate attached to the polymer backbone in the form of acetate groups. These acetate groups can be hydrolyzed to form hydroxyl groups. Furthermore, the polymer may comprise residues of dialkyl maleates linked to the polymer backbone in the form of alkanol groups. These alkanol groups can be hydrolyzed to form carboxylic acid groups.

The polymers may be hyperbranched. In the present application, the term "hyperbranched" is understood in its broadest sense and its use corresponds to the Pure applied chemistry (Pure appl. chem.), Vol.81, No. 6, p.1131-1186, 2009. doi:10.1351/PAC-REC-08-01-30

2009 IUPAC, publication date (network) 5 months 5 days 2009; pure and appliedInternational union of the chemical polymer sector; the Committee for macromolecular nomenclature; the subcommittee of macromolecular terminology based on chemical structure and molecular architecture is in agreement with the subcommittee of polymer-based polymer terminology.

Hyperbranched, in its broadest term, refers to a polymer composed of highly branched macromolecules in which any linear branch can lead in at least two other branches in either direction.

The polymer may be a poly (alkenyl alkanoate) or a poly (alkenyl alcohol) -co (alkenyl alkanoate) or a poly (alkyl alcohol) -co (alkenoate). Thus, for example, the polymer may comprise ester groups, carboxylic acid groups, and hydroxyl groups. The polymer may have a degree of hydrolysis of at least 60 mol%, alternatively at least 65 mol%, alternatively at least 70 mol%, alternatively no greater than 95 mol%, and alternatively no greater than 90 mol%. Their relatively high degree of hydrolysis has been found to play a role in promoting good performance as primary suspending agents in certain polymerization reactions, for example in the polymerization of alkenyl compounds such as vinyl chloride and copolymers thereof.

The polymer can optionally have a weight average molecular weight (M) of at least 3,000, alternatively at least 10,000, alternatively at least 20,000, alternatively at least 40,000, and alternatively at least 50,000_w). The polymer may optionally have a weight average molecular weight of no greater than 60,000, optionally no greater than 70,000, optionally no greater than 80,000, optionally no greater than 100,000, optionally no greater than 200,000, optionally no greater than 300,000, optionally no greater than 400,000, optionally no greater than 500,000, optionally no greater than 750,000, and no greater than 1,000,000g.mol^-1Weight average molecular weight (M) of_w)。

The polymer can optionally have a number average molecular weight (Mn) of at least 1,500, alternatively at least 2,000, alternatively at least 2,500, alternatively at least 3,000, and alternatively at least 4,000. The polymer can optionally have a molecular weight of no greater than 6,000, alternatively no greater than 7,000, alternatively no greater than 8,000, alternatively no greater than 10,000, alternatively no greater than 12,000, alternatively no greater than 15,000, alternatively no greater than 25,000, alternatively no greater than 30,000, alternatively no greater than 50,000, alternatively no greater than 100,000, can beOptionally no greater than 200,000, optionally no greater than 300,000, optionally no greater than 400,000, and optionally no greater than 500,000g.mol^-1Number average molecular weight (M) of_n)。

M_wAnd M_nMeasurements were made by Size Exclusion Chromatography (SEC), also known as gel permeation ion chromatography (GPC), in THF solution. Samples were injected into the PL-GPC-50 system by an autosampler using stabilized THF as the mobile phase and three PL gel columns in series, each having dimensions of 300mm by 7.5mm by 10 μm. The system is used in 6035000-^-1M of (A)_pPS height in the molecular weight range

Polystyrene standards (provided by agilent technologies).

Dispersity of the Polymer (in M)_w/M_nBy definition, commonly referred to as polydispersity, or polydispersity index (PDI)), may be at least 2, at least 3, at least 5, and optionally at least 10. The dispersity can be optionally no greater than 20, optionally no greater than 25, optionally no greater than 30, optionally no greater than 50, optionally no greater than 100, optionally no greater than 150, and optionally no greater than 200. Alternatively, the dispersity of the polymer can be from 3 to 200, alternatively from 5 to 150, alternatively from 3 to 30, and alternatively from 5 to 25.

The hydrolyzed polymer, typically poly (vinyl acetate) -co-poly (vinyl alcohol), can have a viscosity (w/w) at 20 ℃ of a 4% solution of no greater than 50mpa.s, alternatively no greater than 30mpa.s, alternatively no greater than 20mpa.s, alternatively no greater than 10mpa.s, alternatively no greater than 8mpa.s, and alternatively no greater than 5 mpa.s. Optionally, the viscosity is at least 1mpa.s, optionally at least 2mpa.s, and optionally at least 5 mpa.s.

The viscosity of the above 4% (w/w) solution was measured by: the dried material was dissolved in distilled water to give the desired concentration and the desired amount of solution was placed in a calibrated U-tube viscometer (the capillary size of which was chosen to give a flow time of about 60 seconds) and equilibrated to 20 ± 0.2 ℃ in a water bath. The time for the equilibration solution to flow between two markers of the capillary was used to calculate the solution viscosity. The solution viscosity is calculated as follows:

viscosity (flow time recorded) x (4% (w/w) solution density) x (viscometer calibration factor).

Solution viscosity measurements are performed on poly (alkenyl alkanoates), such as poly (vinyl acetate), to determine the K value. In this case, the K value was measured using a 2% (W/V) polymer solution in ethyl acetate in a "C" U-type viscometer equilibrated in a water bath at 20. + -. 0.2 ℃. The time for the equilibration solution to flow between two markers of the capillary was used to calculate the relative solution viscosity.

Relative solution viscosity ═ (2% (w/v) solution flow time recorded)/(ethyl acetate flow time recorded).

The value of K may be at least 10, at least 15, at least 20, and optionally at least 25. The K value can optionally be no greater than 40, no greater than 50, no greater than 60, no greater than 70, no greater than 80, and optionally no greater than 100. The K value can be 20 to 70, alternatively 25 to 60, and alternatively 30 to 60.

The polymers of the present invention optionally contain more than (C ═ C — C ═ O moieties than (C ═ C)₃The CO moiety, optionally C-O moiety, is significantly more than (C ═ C)₃And (3) a CO part. The intensity of the UV absorption peak at 280nm (due to the C-C ═ O moiety), generated by the polymer solution, may optionally be greater than the intensity of the UV absorption peak at 320nm (due to (C ═ C)₃CO fraction), optionally having a peak intensity at 280nm of at least two times, optionally at least three times, optionally at least four times, optionally at least five times, and optionally at least six times the peak intensity at 320 nm. Those skilled in the art will recognize that the exact wavelength at which the peak is observed may vary slightly from 280nm and 320 nm.

For the avoidance of doubt, the intensity of the UV absorption peak is thus measured: a polymer solution or dispersion is formed in distilled water, typically at a concentration of 0.1% or 0.2% (w/w). The UV spectrum of the solution was then recorded on a UV single beam spectrophotometer (Thermo spectral) using a 10mm optical path quartz cell, the spectrum being corrected for solvent/dispersant (water). The absorbance is multiplied by a suitable number (typically 10 or 5, depending on the initial concentration used) to provide the absorbance at a polymer concentration of 1% (w/w).

One skilled in the art will recognise that the polymer of the third aspect of the invention may comprise features as described for the method of the first aspect of the invention. Furthermore, the process of the first aspect of the invention may comprise features of the polymer of the third aspect of the invention and the process of the first aspect of the invention may be used to prepare the polymer of the third aspect of the invention.

According to a fourth aspect of the present invention there is provided the use of a polymer according to the second or third aspect of the present invention in the suspension polymerisation of unsaturated monomers. The polymer is optionally used as a primary suspending agent. Primary suspending agents are commonly used to control particle size and to control agglomeration of particles.

According to a fifth aspect of the present invention there is provided a suspension polymerisation composition comprising a continuous phase having dispersed therein beads of monomer to be polymerised, and a polymer according to the second or third aspect of the present invention.

Typically, primary suspending agents are used on the order of 400ppm and 1500ppm, optionally in combination with 0-2000ppm secondary suspending agent, the exact values depending on reactor geometry, agitation, oxygen levels, additives (e.g. buffers), temperature, presence of reflux condensers, etc. In addition, the primary suspending agent may comprise more than one component; for example, it may comprise 72 mol% hydrolyzed PVOH in combination with 88 mol% hydrolyzed PVOH, optionally in the presence of a cellulosic primary suspension agent. Similarly, for example, the secondary suspending agent may be a low hydrolysis polyvinyl acetate (typically less than 60 mol%), a cellulosic material, or a non-ionic surfactant such as sorbitan monolaurate, or a combination thereof. The continuous phase may be aqueous. The monomers may comprise alkenyl compounds such as vinyl chloride and copolymers thereof. The terms "primary suspending agent" and "secondary suspending agent" are well known to those skilled in the art. The primary suspending agent generally controls the agglomeration of the polymer particles and therefore primarily determines the size of the polymer particles so formed. Secondary suspending agents generally determine secondary characteristics of the polymer particles, such as particle shape and porosity. The secondary suspending agent typically comprises partially hydrolyzed polyvinyl acetate (typically having a degree of hydrolysis of about 55 mol%).

Embodiments of the present invention will now be described by way of illustration only.

Detailed Description

In the following description, the following abbreviations or terms are used:

IPA-isopropyl alcohol (2-propanol)

TTT-1, 3, 5-triallyl-1, 3, 5-triazine-2, 4, 6-trione

M_nNumber average molecular weight

M_wWeight average molecular weight

PDI-M_w/M_n

K-K value

RA-residual acetate (% (w/w))

Degree of hydrolysis of DH-mol%)

MeOH-methanol

VAc-vinyl acetate

AIBN-azobisisobutyronitrile

AIVN-azobis (2-methylbutyronitrile)

^tBP2 EH-peroxy-2-ethylhexanoic acid tert-butyl ester

CTA-chain transfer agent

4-L/SP-4 liter volume reactor

1-L/SP-1 liter volume reactor

UV₂₈₀Intensity of UV absorption peak at 280nm expressed in 1% (w/w) concentration

UV₃₂₀Intensity of UV absorption peak at 320nm, expressed in 1% (w/w) concentration

DH-degree of hydrolysis (mol%) -degree of hydrolysis was calculated from the Residual Acetate (RA) value. The residual acetate value of the polymer was measured by refluxing with a known excess of 0.1N sodium hydroxide solution. A blank assay without polymer was also performed. The remaining sodium hydroxide was titrated with 0.1N hydrochloric acid using phenolphthalein indicator. The residual acetate in the polymer was calculated using the following formula.

Residual acetate (% (w/w) ═ V_{Blank space}–V_Titration) X 0.86)/weight of sample

Degree of hydrolysis (mol%) ((100X 1.9545 (100-RA))/[ (1.9545(100-RA)) -RA) ]

Viscosity of 4% (w/w) the viscosity of a 4% (w/w) solution of poly (vinyl alcohol) -co-poly (vinyl acetate) was determined as described above.

TSC-total solids content. The percentage of Total Solids Content (TSC) was determined by weighing samples of the material before and after drying them in a vacuum oven at about-900 to-1000 mbar and 105 ℃ for 1 hour.

MH-Mark-Houwink (Mark-Houwink) constant

This is generated by the SEC software and data acquisition is provided using Warran, Inc. of America

Version 3.2 GPC/SEC on Multi-line. Data analysis was performed using a data analysis system provided by Warran, USA

Multiple offline GPC/SEC version 3.2.

The Mark-Houwink (Mark-Houwink) equation is used to describe the relationship between intrinsic viscosity and relative molecular weight of a polymer:

[η]＝K.M_r ^a

where [ η ] ═ intrinsic viscosity, and K and 'a' are constants (commonly known as Mark-Houwink constants), which depend on the nature of the polymer and solvent, and also on temperature, and are usually one of the relative molecular weight averages (http:// goldbook. iupac. org/m03706. html). For a given polymer (hydrolyzed to the same degree) in the same solvent at the same temperature and concentration, K will be constant, and only the exponential term 'a' will reflect the linear or branched nature of the polymer. It is widely accepted that in these cases a decrease in the value of a indicates an increase in the degree of branching/hyper-branching.

D₅₀This is a measure of the particle size of the PVC, determined as follows. 12.5g of resin were weighed and placed in a stackSix screens with 315, 250, 200, 160, 100 and 75 micron openings respectively and a collection pan for collecting any passing 75 micron screens. The stack was fixed to a shaker and shaken for 15 minutes. The weight of resin in each screen was recorded and each value was divided by 12.5 to measure the fraction of the total mass captured by the screen. The values are plotted on a logarithmic graph and when 50% of mass is reached, the values are determined.

GSD-particle size distribution. GSD uses D₅₀The resulting graph from the particle size measurement determined the particle size at 16% by mass of the resin and at 84% by mass of the resin. GSD was then determined by bisecting the difference between the particle size at 84% mass and the particle size at 16% mass and dividing the bisection by D₅₀To calculate.

BD-bulk density. The resin was quantitatively placed in a fluid bed dryer and dried at 50 ℃ for one hour. The resin was cooled for one hour. The resin was then poured through a funnel into exactly 100cm³In a stainless steel vessel in accordance with ASTM 1895B. A sharp blade was used to flatten the resin pile and the container was weighed. Bulk density is calculated from the mass and volume of resin in the vessel.

CPA (cold plasticizer absorption) of CPA-PVC can be determined by carefully weighing 2.5g of resin and 4g of dioctyl phthalate (plasticizer) into a container containing the film. The container was capped and centrifuged at 3000rpm for 1 hour (to obtain the same value as the ASTM standard). The container is reweighed to determine the mass of plasticizer that has been absorbed by the resin. The percentage value with respect to the mass of the resin can be calculated.

The fill factor of PF-PVC is a measure of how the particles of resin pack together. It is calculated as follows:

PF＝((l+0.014CPA)(0.1BD)/1.4

all samples of the resin were washed twice with 1% (w/w) sodium lauryl sulfate and dried in a 50 ℃ oven overnight prior to testing. The resin was then weighed, placed in the oven for an additional hour, and then reweighed. Only when the mass no longer dropped more than 1.0g was it considered dry enough to be tested.

The invention will now be described by way of example only.

All materials were used as supplied without further purification. All materials were obtained from Aldrich (Aldrich) with the exception of AIBN (from Pergan ltd), IPA (from Fisher Scientific), methanol (from brentag ltd or japan mitsui european public ltd) and vinyl acetate (from brentag ltd or linard industrial n.v. (LyondellBasell industris n.v.)).

Examples of the process of the invention are carried out by solution polymerization and suspension polymerization. First, an example of the method of the present invention using solution polymerization will be described.

A-general Process for preparing PVAc Using solution polymerization

Monofunctional monomer (typically vinyl acetate), polyfunctional monomer (TTT in this example), initiator (typically AIBN), solvent (methanol and/or IPA), and CTA (typically propanal) were mixed in a reactor flask (typically a 1-liter flask) and deoxygenated with nitrogen for 30 minutes. The mixture is then heated to the reaction temperature (typically 70 ℃). If more components (such as CTA) are to be added, they are typically added over a period of one hour thereafter (although this period may be longer than one hour). The reaction was then held at the reaction temperature for an additional 4 hours (5 hours total at the reaction temperature). Excess liquid was then removed by distillation and methanol was added at constant feed for 4 hours to maintain a viable viscosity.

B-preparation of PVOH from PVAc

The PVAc prepared by the method generally described in "A" above was hydrolyzed using a 45% (w/w) solution of PVAc in methanol. Generally, 14mL of catalyst (10% (w/w) NaOH in methanol) was used per 100g of polymer. It is sometimes necessary to use a larger amount of catalyst (e.g., up to 20mL of catalyst (10% (w/w) NaOH in methanol) per 100g of polymer). The Hydrolysis of PVAc to PVOH using sodium hydroxide solution is known to those skilled in the art, for example GB749458 and described in "Polyvinyl Alcohol development (Polyvinyl Alcohol definitions)", edited by c.a. fine, (C)1992 John Wiley & Sons Ltd, chapter 3: Hydrolysis of Polyvinyl Acetate to Polyvinyl Alcohol (Hydrolysis of Polyvinyl Acetate to Polyvinyl Alcohol), by f.l. marten; zvanut, pages 57-77. The scope of the claims of this application may include any features disclosed in these documents. In particular, the scope of the claims of the present application may be modified to include features described in these documents with respect to hydrolyzing ester monomer residues on the polymer chain.

For the avoidance of doubt by way of illustration, polyvinyl alcohol also includes poly (vinyl alcohol), partially hydrolyzed poly (vinyl acetate), partially hydrolyzed polyvinyl acetate, and PVOH.

For the avoidance of doubt by the use of instructions, polyvinyl acetate also includes poly (vinyl acetate) and PVAc.

Examples of polyvinyl acetate polymers prepared using the general process described above in "a" are now described with reference to table 1. The examples labeled "c.ex" are comparative examples and are not within the scope of the invention.

The solvent is IPA and/or methanol. The CTA was propionaldehyde, all of which was initially present in the reaction mixture, i.e., no delayed addition of CTA. The reaction time was 5 hours and the reaction temperature was 70 ℃.

The above examples illustrate that satisfactory conversion can be obtained, but considerable IPA levels are required to inhibit gelation in view of the amount of CTA and TTT present in the reaction mixture.

TABLE 1

ND could not be measured due to gelation

Further examples are now described with reference to table 2, which shows that delayed addition of CTA inhibits gelation.

TABLE 2

Propanal feed rate not controlled

The polymers in table 2 were synthesized using the general method described above. IPA (isopropyl alcohol)_ini、MeOH_iniAnd propionaldehyde_iniRefers to the amount of IPA, methanol, and propionaldehyde initially in the reaction mixture. 248.8g of VAc, 1.20g of TTT and 9.5g of AIBN were initially also present in the reaction mixture. After the reaction mixture was brought to the reaction temperature, more propionaldehyde (propionaldehyde) was continuously added over one hour_del) (together with methanol, labeled MeOH)_del)。

The examples of Table 2 illustrate that by delaying the addition of at least some CTA, it is possible to obtain a polymer without gelling, even if no or a small amount of IPA is present. The examples of table 2 illustrate that controlled addition is preferred; in example 25, gelation was observed without controlled delayed addition of propionaldehyde, whereas in example 26, with controlled delayed addition of propionaldehyde, no gel was formed. In the above examples, methanol is the preferred solvent because it has a lower chain transfer constant than IPA and therefore less solvent residue is included in the polymer. This is desirable because it is desirable to include more CTA residues to increase the amount of carbonyl groups in the polymer.

A study was conducted to determine the properties of polyvinyl alcohols prepared by the methods generally described in "a" and "B" above. Examples of the polyvinyl alcohol produced will now be described with reference to table 3. Unless otherwise indicated, the vinyl acetate polymers of the examples of Table 3 were synthesized at 70 ℃ initially in the reaction mixture as 248.8g of VAc, 1.20g of TTT, 9.5g of AIBN and 6.79g of propionaldehyde and 213.9g of MeOH, 23.5g of propionaldehyde was added continuously to the reaction mixture over an hour, and the reaction was held at reaction temperature for an additional 4 hours after propionaldehyde had been added. The polyvinyl acetate thus obtained is then hydrolysed to form polyvinyl alcohol.

TABLE 3

Comparative example 2-No TTT, propionaldehyde_ini5.82g, propionaldehyde_del＝20.6g；

Comparative example 3-No TTT, VAc 300g, propionaldehyde_ini5.82g, propionaldehyde_del＝20.6g；

TTT from example 27 to 0.7 g;

example 28-VAc 265g propionaldehyde_del＝25g；

Example 29 MeOH_ini＝163.9g、MeOH_del＝50g；

Comparative example 4 use of IPA instead of propionaldehyde and IPA_ini＝24.4g、IPA_del＝100g；

Example 32 MeOH_ini163.9g, 1.45g TTT, propionaldehyde_ini8.5g, propionaldehyde_del＝24.5g、MeOH_del＝50g

Example 33-TTT 1.7g propanal was added "in aliquots" (5.66g was added in aliquots for t 10-20-30-40-50-60 min).

The use of the subscript "ini" refers to the amount of the particular ingredient initially present in the reaction mixture. The subscript "del" is used to refer to the amount of the ingredient added with delay.

The parameters listed in table 3 above were determined for polyvinyl alcohol, except that the K value was measured for polyvinyl acetate.

The examples of table 3 illustrate that it is possible to prepare polymers with high TTT concentrations by using correspondingly large amounts of CTA and delaying and controlling the addition of at least some of the CTA. For example, for example 38, 10.1g of propionaldehyde was initially added followed by 43g over about one hour. The examples in Table 3 further illustrate that increasing the amount of TTT increases the intensity of the UV absorption peak at 280nm, indicating that- (C ═ C)₂The concentration of C ═ O group can be usedIncreases the amount of TTT. The intensity of the UV absorption peak at 320nm did not increase significantly with the amount of TTT used, indicating (C ═ C)₃The concentration of C ═ O species did not increase significantly. In addition, the small peak observed at 320nm is consistent with the white coloration of the polymer. The Mark-Houwink constant decreased with increasing amount of TTT used, indicating that an increase in TTT would result in a greater amount of branching.

Further experiments were conducted to investigate the effect of making polyvinyl acetate in a 4 liter reactor (relative to a 1 liter reactor).

TABLE 4

Polyvinyl acetate was prepared using the general methods described above in connection with table 3. The polyvinyl acetate is then hydrolyzed as described above in "B". The intensity of the UV absorption peak at 280nm increases with the amount of TTT used. The viscosity of solutions of polyvinyl alcohol is generally low, indicating that the branching properties of the polymer are retained after hydrolysis.

Six polymer samples were submitted for GPC analysis.

TABLE 4A

Experiments were conducted to confirm whether the method described above is suitable for replacing the tri-unsaturated monomer and TTT with other tri-unsaturated monomers. Examples of polyvinyl alcohol made using diallyl maleate (DAM) will now be described with reference to table 5.

TABLE 5

Example 38 use of TTT, not DAM

Polyvinyl acetate is prepared using the general method described above. All reactions were carried out at 70 ℃, VAc ═ 248.8g, MeOH ═ 214g, AIBN ═ 9.5g, and DAM ═ 1.9 g. The CTA (propionaldehyde) was added over a period of one hour, and then the reaction mixture was held at the reaction temperature for an additional 4 hours. The initial charge of propionaldehyde at the start of the addition was 10.1g, and 11.0g in examples 40, 41, and 42, respectively. The addition of a further amount of propionaldehyde (43.0 g, 47.6g and 60.0g for examples 40, 41 and 42, respectively) took one hour.

It was observed that when DAM was used instead of TTT, a larger amount of propionaldehyde was required to avoid gel formation. For polymers made using DAM, UV2₈₀The intensity of the absorption peak is slightly greater than that of the polymer obtained using TTT, indicating that (C ═ C)₂The concentration of the C ═ O moiety is slightly greater. The K value for example 42 (made using DAM) was greater than that for example 38 (made using TTT), but the 4% viscosity measurements were similar, indicating that some branches may have been cleaved during hydrolysis. The effect of delayed feeding of monofunctional monomers and optionally multifunctional monomers was investigated and the results are shown in table 6 below.

TABLE 6

ND is indeterminate.

Example 43 initial mixture-MeOH 250g, VAc_ini200g, 1.2g TTT, 9.5g AIBN, propionaldehyde_ini6.79 g. Delayed addition of propionaldehyde 33.8g and VAc 100g

Example 44 initial mixture-MeOH 250g, VAc_ini200g, 1.2g TTT, 9.5g AIBN and propionaldehyde_ini6.79 g. Delayed addition of 25g propionaldehyde and 100g VAc

Example 45 initial mixture-MeOH 250g, VAc_ini200g, 1.2g TTT, 9.5g AIBN and 6.79g propionaldehyde ini. Delayed addition of 25g propionaldehyde and 50g VAc

Examples 46-48-initial mixture-MeOH 250g, VAc_ini50g, AIBN 9.5g and propionaldehyde_ini10.1 g. Delayed addition of 43g propionaldehyde, 2.15g TTT and 199g VAc

Example 48-the desired degree of hydrolysis was not achieved.

Example 49 initial mixture-MeOH 250g, VAc_ini50g, AIBN 9.5g and propionaldehyde_ini10.1 g. Delayed addition TTT 2.15g and VAc 199 g. Delayed addition propionaldehyde 43g, separated from delayed feeds of VAc and TTT.

The feed time in each example represents the time elapsed for the addition of the delayed addition component. The total reaction time (including the feed time) was 5 hours in each example. Many of the examples above show the synthesis and properties of polyvinyl acetate and polyvinyl alcohol prepared using solution polymerization.

The effect of the type of initiator on the polymer properties was investigated.

The polymers in table 7 below were synthesized and characterized using the general methods described above for "a" and "B". The vinyl acetate polymer in the examples was typically polymerized at 70 ℃ initially present in the reaction mixture as 248.8g of VAc, 2.15g of TTT, 10.1g of propionaldehyde and MeOH (typically 214g, but varying from example to example); propionaldehyde 43g was added continuously to the reaction mixture over one hour. After all the propionaldehyde had been added, the polymerization was held at the reaction temperature for an additional 4 hours. The initiator and the method of feeding the initiator are described below. The polyvinyl acetate thus obtained is then hydrolyzed to polyvinyl alcohol according to the general method described hereinbefore.

TABLE 7

"I" in the third column represents an initiator;

in the following examples 101 to 106, the subscript "ini" refers to the amount initially in the reaction mixture.

Example 101 AIBN_ini4.94 g. After 45 minutes of polymerization, AIBN ═ 1.14g was added as 1 aliquot.

Example 102 MeOH_ini＝209g、AIVN_ini6.5 g. After 45 minutes of polymerization, it was dissolved in 5g ofAIVN in MeOH ═ 1.5g was added as 1 aliquot

Example 103-^tBP2EH_ini3.5 g. After polymerization for 45 minutes and 1 hour and 30 minutes, the polymerization solution was added^tBP2EH ═ 1.5g and other aliquots

Example 104-^tBP2EH_ini3.5 g. After a polymerization time of 45 minutes had elapsed,^tBP2EH ═ 1.5g was added as 1 aliquot. The unhydrolyzed polyvinyl acetate of example 104 has M_n＝3700g.mol^-1、M_w＝334900g.mol^-1、PDI＝91、MH＝0.42。

Example 105 MeOH_ini＝194g、^tBP2EH_ini1.5 g. Dissolved in 20g MeOH^tBP2EH ═ 2g was added in a delayed manner, but continuously over 2 hours and 30 minutes.

Example 106 MeOH_ini＝194g、^tBP2EH_ini0.5 g. Dissolved in 20g MeOH^tBP2EH ═ 1.5g was added in a delayed manner, but continuously over 2 hours and 30 minutes.

As can be seen from table 7, the use of different initiators on vinyl acetate, or different molar amounts of initiators, or different initiator addition schemes, did not significantly affect the properties of polyvinyl acetate and polyvinyl alcohol. UV (ultraviolet) light₂₈₀The intensity of the absorption peak, K value and 4% solution viscosity measurements were similar and similar to those described above.

The examples in Table 7 illustrate that, using various initiators capable of generating free radicals, it is possible to prepare polymers that do not gel and retain the characteristics of the final polyvinyl alcohol. Furthermore, sufficiently high UV absorption values can be generated by adding the initiator to the initial monomer feed at the start of the polymerization, or by a combination of an initial feed of initiator and a delayed feed.

TABLE 7.1 unhydrolyzed polyvinyl acetate

The data shown in table 7.1 confirm the formation of hyperbranched polyvinyl acetate.

Effect of changing chain transfer agent

TABLE 8

Propionaldehyde was used in examples 104 and 108, while butyraldehyde was used in examples 109 and 111.

Example 104 propionaldehyde_ini10.1g, propionaldehyde_del＝43.0g；

Example 108 propionaldehyde_iniNot equal to 8.0g, propionaldehyde_del＝34.0g；

Example 109 butyraldehyde_ini12.54g of butyraldehyde_del＝53.4g；

Example 110 butyraldehyde_ini10.1g of butyraldehyde_del＝43.0g；

Example 111 butyraldehyde_ini11.6g of butyraldehyde_del＝49.5g；

Polyvinyl acetate is prepared using the general method described above. All reactions were carried out at 70 ℃ using VAc 248.8g,^tBP2EH ═ 3.5g, TTT ═ 2.15g, MeOH ═ 214g, and the initial amounts of chain transfer agent (indicated by subscript "ini") were initially present in the reaction mixture, and the amount of chain transfer agent was added continuously to the polymerization mixture over the course of one hour (indicated by subscript "del"). After all the chain transfer agent was added, the polymerization was held at 70 ℃ for another 4 hours. After 45 minutes of polymerization, an aliquot of 1.5g of^tBP2EH。

The results shown in table 8 show that UV when butyraldehyde is used as a chain transfer agent (on an equimolar amount basis) in place of propionaldehyde₂₈₀The intensity of the absorption peak increases significantly. Without being limited by theory, this observation indicates that when butyraldehyde is used, a greater concentration of the desired (C ═ C) is present₂And C ═ O moieties. The K values and 4% solution viscosity values obtained for example 109 and example 110 (prepared using butyraldehyde) are lower than those obtained for example 107 and example 108 (prepared using propionaldehyde), respectively. Without being limited by theory, this is consistent with the more chain transfer reactions that occur with butyraldehyde.

TABLE 8.1 unhydrolyzed polyvinyl acetate

The data shown in table 8.1 confirm the formation of hyperbranched polyvinyl acetate.

Different polymerization schemes were investigated using the general methods described in "a" and "B" above.

TABLE 9

Example 112 initial mixture MeOH 200g, VAc_ini＝100g、TTT_ini＝0.7g、^tBP2EH_ini＝3.5g、^tBP2EH ═ 1.5g was added after 45 minutes of polymerization. After the start of the polymerization, 14g of MeOH, 1.45g of TTT and 148.8g of VAc, which were added with delay, were added over 1 hour. After the start of the polymerization, propionaldehyde was added with a delay of 36.5g over 1 hour, separately from the delayed feeds of VAc and TTT.

Example 113 initial mixture-MeOH 214g, VAc_ini＝100g、TTT_ini＝0.7g、^tBP2EH_ini＝3.5g、^tBP2EH ═ 1.5g was added as an aliquot after 45 minutes of polymerization. Delayed addition TTT 1.45g and VAc 148.8g were added over 1 hour after the start of the polymerization. After the start of the polymerization, 32.9g of propionaldehyde added in a delayed addition over 1 hour were added separately from the delayed feeds of VAc and TTT.

Example 114 initial mixture-MeOH 210g, VAc_ini＝248.8g、TTT_ini＝0.71g、^tBP2EH_ini＝3.5g、^tBP2EH ═ 1.5g was added as an aliquot after 45 minutes of polymerization. At the beginning of the polymerizationThereafter, 2g of meoh with 0.72g of TTT were added several times, once 45 minutes after the start of the polymerization and once 1 hour 15 minutes later. After the start of the polymerization, a delayed addition of 43g of propionaldehyde was carried out for 1 hour and 30 minutes.

Example 115 initial mixture-MeOH 210g, VAc_ini＝248.8g、TTT_ini＝0.71g、^tBP2EH_ini＝3.5g、^tBP2EH ═ 1.5g was added as an aliquot after 45 minutes of polymerization. After the start of the polymerization, multiple additions of 0.72g TTT in 2g meoh were made, once 45 minutes after the start of the polymerization and once 1 hour 15 minutes later. After the start of the polymerization, a delayed addition of 30.6g of propionaldehyde was carried out for 1 hour and 30 minutes.

Example 116 initial mixture-MeOH 196.2g, VAc_ini＝248.8g、^tBP2EH_ini＝3.5g、^tBP2EH ═ 1.5g was added after 45 minutes of polymerization. After the start of the polymerization, delayed additions of 21.4g of MeOH and 2.15g of TTT were made over 1 hour. After the start of the polymerization, a delayed addition of 43g of propionaldehyde, separated from the delayed feed of TTT, was also carried out for 1 hour.

Example 117-initial mixture-MeOH 856g, prepared from VAc 995.2g, TTT 8.6g, and,^tBP2EH ═ 14g and propionaldehyde 127.6 g. 20% by weight of the mixture was initially fed to the reactor and the remaining 80% of the mixture was added as a delayed addition over 2 hours and 30 minutes before the start of the polymerization. The batch was then cooked at 80 ℃ for 2 hours and 30 minutes.

Example 118 initial mixture-MeOH 210g, VAc_ini＝248.8g、TTT_ini＝0.71g、^tBP2EH_ini＝3.5g、^tBP2EH ═ 1.5g was added as an aliquot after 45 minutes of polymerization. After the start of the polymerization, multiple additions of 0.72g TTT in 2g meoh were made, once 45 minutes after the start of the polymerization and once 1 hour 15 minutes later. After the start of the polymerization, a delayed addition of 43g of propionaldehyde was carried out for 1 hour and 30 minutes.

TABLE 9.1 unhydrolyzed polyvinyl acetate

The data shown in table 9.1 confirm the formation of hyperbranched polyvinyl acetates.

Further embodiments of the polymers of the present invention are synthesized using a suspension polymerization process.

C-suspension polymerization to prepare PVAc

1200g of H₂O, 216g of salt, 1.36g of cellulose ether, 0.44g of sodium carbonate, 4.44g of tetrasodium pyrophosphate, 7.28g of sodium bicarbonate, 0.4ml of formic acid and 0.6ml of defoamer were fed to a 4 liter reactor at 30 ℃ and mixed for 30 minutes. 900g of VAc, 5.8g of TTT and 89.8g of propionaldehyde solution are added and the temperature is raised to 59 ℃ in a water bath. After 10 minutes at 59 ℃ 35g of AIBN dissolved in 100g of VAc were added and the temperature was set at 72 ℃. After the reflux was complete, the suspension was kept at 88 ℃ for 30 minutes and then distilled at 120 ℃ for 1 hour and 45 minutes. Once the reaction has cooled to 40 ℃, 44g of salt are added and the reaction medium is stirred for 1 hour before cooling.

D-formation of PVOH from PVAc made by suspension polymerization

The beads prepared according to "C" above were extracted, washed with water and dried overnight. The solution was prepared by dissolving the beads at 45 (w/w)% in methanol. This solution was then used for hydrolysis, using 14mL of methanol in sodium hydroxide (10% (w/w)) for 100g of polymer (as described above in connection with the solution polymerization).

The examples of table 10 show the preparation of PVAc and PVOH using a suspension polymerization process.

Watch 10

The examples in table 10 show that it is possible to prepare polyvinyl acetate and polyvinyl alcohol according to the invention using suspension polymerization. In addition, there is no need to delay feeding CTA to prevent gelation. Without being bound by theory, this may be a result of the relatively high solubility of propionaldehyde in water, which reduces contact between CTA and monomer.

Some examples of polyvinyl alcohol described above are used as primary suspending agent in suspension PVC polymerization processes, whether in a 1-liter reactor or a 10-liter reactor.

1 liter reactor conditions

Various samples of the poly (vinyl chloride) component were prepared based on the following formulation:

TABLE 11

Demineralized water, suspending agent, buffer and initiator were all charged to a 1 liter distributed (Biichi) stainless steel reactor (which had been supplied beforehand by Synthomer (UK) Ltd

225 build-up inhibitor coating) and assembled to the tool. The formulation in table 11 was designed to give a final particle size consistent with conventional commercial products. The reactor pressure was then tested, degassed to atmospheric pressure, and then vinyl chloride monomer was fed under nitrogen pressure through a volumetric pressure device (volumeric bomb). A suspension of vinyl chloride was prepared with stirring at about 750 rpm. The reactor was then heated to the desired polymerization temperature in the range of 57 ℃ over 6 minutes with stirring at 750rpm, stirring was continued at about 750rpm, the maximum pressure was recorded, and the reaction was stopped after a pressure drop of 0.2MPa (by cooling and degassing to atmospheric pressure). The reactor was then subjected to a vacuum of about 50kPa for 45 minutes. The reactor contents were then transferred to a filter funnel and washed twice with 1% (w/w) sodium lauryl sulfate solution (as an antistatic treatment). The samples were then dried in a circulating fan oven at 50 ℃ for 12 hours. Thereafter, PVC analysis was performed and the results are shown in table 12.

The results obtained in the 1 liter reactor are shown in table 12 below.

TABLE 12

Comparative example 6 ═

B72-available from Simmer (Synthomer) (UK)

Comparative example 7 ═

80-available from Simmer (Synthomer, UK) Inc

Those skilled in the art will recognize the TTT used in tables 12 and 13: VAc, DH, UV₂₈₀And UV₃₂₀Refers to the properties of PVOH used as a suspending agent, and D₅₀GSD, CPA, BD and PF are properties of polyvinyl chloride.

10 liter reactor conditions

The monomer is vinyl chloride. PVOH example was added at 1300 ppm. No secondary suspending agent is used. The buffer was 200ppm (as a 1% (w/w) solution of sodium bicarbonate). The initiator was 1000ppm of bis (4-tert-butylcyclohexyl) peroxydicarbonate. The reaction temperature is 57 ℃, and the coating is carried out

A225 liter stainless steel reaction vessel containing the build-up inhibitor was operated with a standard stirrer operating at a stirrer speed of 600 rpm.

The results obtained using the 10 liter reactor are shown in table 13 below.

Watch 13

Comparative example 8 ═

72.5-obtained from Simmer (Synthomer) (UK) Ltd

Comparative example 9 ═

78-available from Simmer (Synthomer) Inc.

The data in tables 12 and 13 show that the polyvinyl alcohols according to the invention are successfully used as primary suspending agents in the preparation of PVC.

The data further show that the polyvinyl alcohol of the invention has a significant effect on reducing the particle size of PVC. Without wishing to be bound by theory, this is expected to be associated with the highly branched nature of polyvinyl alcohol and with- (C ═ C)₂The presence of the moiety C ═ O is relevant. In fact, it can be seen that UV₂₈₀Intensity of peak with D₅₀There is an inverse correlation between the measured particle sizes, i.e. UV₂₈₀The greater the intensity of the peak, the smaller the polymer particle size. In addition, the polyvinyl alcohols of the present invention are generally white, or off-white, and not yellow, orange, or brown. This lack of coloration may be desirable.

While the invention has been described and illustrated with reference to specific embodiments, it will be understood by those skilled in the art that the invention lends itself to many different variations not specifically illustrated herein. By way of example, some possible variations will now be described.

The polymers of the above examples are made from one monofunctional monomer and one multifunctional monomer, and those skilled in the art will recognize that more than one monofunctional monomer and/or more than one multifunctional monomer may be used.

The above examples show the use of vinyl acetate as a monofunctional monomer. One skilled in the art will recognize that other monofunctional monomers (e.g., acrylates) may be used as comonomers.

Likewise, other multifunctional monomers than those described in the above embodiments may be used. The above examples illustrate the use of propionaldehyde or butyraldehyde as the chain transfer agent. Other carbonyl-containing chain transfer agents may be used.

The example of PVC polymerization shown in this application is of the type known as cold feed (cold charged) with primary and secondary suspending agents present at the start of the feed. Other methods are known. Generally, water, protective colloid and further optional additives are first fed into the reactor, and then liquefied vinyl chloride monomer and optional comonomers are added. Alternatively, the feed of protective colloid may be passed simultaneously with the vinyl chloride monomer into a preheated reactor containing some or all of the aqueous phase. Alternatively, the protective colloid may be fed simultaneously with some or all of the heat softened water, in such a way that an aqueous phase is formed, the reactor being at or near the desired polymerization temperature when water, colloid and monomer (e.g., vinyl chloride) are fed. This process is referred to as "hot feed". Optionally, an initiator is then fed into the reactor.

Furthermore, it is known in the prior art that polyvinyl alcohol which can be used as a primary suspending agent in the polymerization of PVC can also be used to stabilize initiator dispersions which can be used in the polymerization of PVC, see for example WO 9818835.

The polyvinyl alcohol primary suspending agents can be used together with other protective colloids, such as other primary protective colloids, with secondary and tertiary protective colloids. Specific examples of protective colloids are listed in Ullmann's Encyclopedia of Industrial Chemistry, 5 th edition, 1992, page 722, Table 3.

In the foregoing description, integers or elements having known, obvious or foreseeable equivalents are mentioned which are incorporated herein as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. The reader will appreciate that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it will be understood that these optional integers or features may be beneficial in some embodiments of the invention but may not be desirable in other embodiments and therefore may not be present in other embodiments.

Claims (51)

1. A process for preparing a branched polymer comprising (C ═ C) -CO groups by free radical polymerization, the process comprising:

(i) providing in mixture at least one monofunctional monomer comprising one polymerizable carbon-carbon double bond per monomer, at least one multifunctional monomer comprising at least two polymerizable carbon-carbon double bonds per monomer, at least one chain transfer agent comprising an aldehyde or ketone, and optionally at least one polymerization initiator;

(ii) forming a polymer from the mixture; and

(iii) hydrolyzing the polymer, thereby forming a hydrolyzed polymer, wherein the ratio of the number of moles of chain transfer agent comprising aldehyde or ketone to the number of moles of multifunctional monomer is at least 10:1 and no greater than 300: 1.

2. The method of claim 1, wherein at least one of the chain transfer agents comprising an aldehyde or ketone comprises 1 to 6 carbon atoms.

3. The method of claim 2, wherein the amount of chain transfer agent comprising an aldehyde or ketone is at least 5 mol% and no greater than 50 mol% of the amount of monofunctional monomer.

4. The method of claim 3, wherein the amount of chain transfer agent comprising an aldehyde or ketone is 10 to 45 mol% of the amount of monofunctional monomer.

5. The method of claim 1, wherein the ratio of the number of moles of chain transfer agent comprising an aldehyde or ketone to the number of moles of multifunctional monomer is from 30:1 to 300: 1.

6. The method of claim 1, wherein the ratio of the number of moles of chain transfer agent comprising aldehyde or ketone to the number of moles of multifunctional monomer is from 50:1 to 250: 1.

7. The method of claim 1, wherein the ratio of the number of moles of chain transfer agent comprising aldehyde or ketone to the number of moles of multifunctional monomer is from 60:1 to 200: 1.

8. The process of any preceding claim, wherein all of the chain transfer agent comprising an aldehyde or ketone is mixed with one or more of at least one monofunctional monomer and at least one multifunctional monomer at the beginning of the polymerization reaction.

9. The process of any one of claims 1-7, wherein all of the chain transfer agent comprising an aldehyde or ketone is mixed with one or more of at least one monofunctional monomer, at least one multifunctional monomer, and at least one polymerization initiator at the beginning of the polymerization reaction.

10. The method of claim 1, wherein the method comprises delaying the addition of at least some of the chain transfer agent comprising an aldehyde or ketone.

11. The method of claim 10, comprising delaying the addition of at least 0.0001% of the chain transfer agent comprising an aldehyde or ketone.

12. The process of claim 11 comprising adding at least 0.001% of the chain transfer agent between 0.001% and 70% conversion.

13. The process of claim 12, wherein no chain transfer agent comprising an aldehyde or ketone is added to the reaction mixture at the start of the polymerization reaction.

14. The method of any one of claims 10-13, comprising adding at least 50% of the chain transfer agent before a percent conversion of the monofunctional monomer reaches 60%.

15. The process of any one of claims 10-13, comprising providing at least a portion of the chain transfer agent comprising an aldehyde or ketone in a mixture of one or more of at least one monofunctional monomer and at least one multifunctional monomer prior to the start of the polymerization reaction.

16. The method of claim 14, comprising providing at least a portion of the chain transfer agent comprising an aldehyde or ketone in a mixture of one or more of at least one monofunctional monomer and at least one multifunctional monomer before the polymerization reaction begins.

17. The method of any one of claims 10-13, comprising providing at least a portion of the chain transfer agent comprising an aldehyde or ketone in a mixture of one or more of at least one monofunctional monomer, at least one multifunctional monomer, and at least one polymerization initiator prior to the start of the polymerization reaction.

18. The method of claim 14, comprising providing at least a portion of the chain transfer agent comprising an aldehyde or ketone in a mixture of one or more of at least one monofunctional monomer, at least one multifunctional monomer, and at least one polymerization initiator prior to the start of the polymerization reaction.

19. The method of any one of claims 10-12, comprising providing at least 5% of the chain transfer agent comprising an aldehyde or ketone in a mixture of one or more of at least one monofunctional monomer and at least one multifunctional monomer before the polymerization reaction begins.

20. The method of claim 14, comprising providing at least 5% of the chain transfer agent comprising an aldehyde or ketone in a mixture of one or more of at least one monofunctional monomer and at least one multifunctional monomer before polymerization begins.

21. The method of any one of claims 10-12, comprising providing at least 5% of the chain transfer agent comprising an aldehyde or ketone in a mixture of one or more of at least one monofunctional monomer, at least one multifunctional monomer, and at least one polymerization initiator prior to the start of the polymerization reaction.

22. The method of claim 14, comprising providing at least 5% of the chain transfer agent comprising an aldehyde or ketone in a mixture of one or more of at least one monofunctional monomer, at least one multifunctional monomer, and at least one polymerization initiator prior to the start of polymerization.

23. The method of any one of claims 1-7, comprising providing more than one monofunctional monomer, each of the monofunctional monomers comprising one and only one polymerizable carbon-carbon double bond.

24. The method of any one of claims 1-7, wherein at least one of the multifunctional monomers comprises a difunctional monomer, a trifunctional monomer, a tetrafunctional monomer, or a pentafunctional monomer.

25. The method of any one of claims 1-7, wherein the amount of multifunctional monomer is at least 0.05 mol% of the amount of monofunctional monomer.

26. The method of any one of claims 1-7, wherein the amount of multifunctional monomer is no more than 5 mol% of the amount of monofunctional monomer.

27. The method of any one of claims 1-7, wherein the amount of multifunctional monomer is no more than 2 mol% of the amount of monofunctional monomer.

28. The method of any one of claims 1-7, wherein the amount of multifunctional monomer is no more than 1 mol% of the amount of monofunctional monomer.

29. The method of any one of claims 1-7, wherein the amount of multifunctional monomer is no greater than 0.8 mol% of the amount of monofunctional monomer.

30. The method of any one of claims 1-7, wherein the amount of multifunctional monomer is 0.1 to 0.5 mol% of the amount of monofunctional monomer.

31. The method of any one of claims 1-7, wherein the free radicals are generated using one or more of a polymerization initiator and exposure to electromagnetic radiation of an appropriate wavelength.

32. The method of any one of claims 1-7, wherein the free radicals are generated using a redox chemical.

33. The method of any one of claims 1-7, comprising solution polymerization, for which is a single solvent, or a plurality of solvents comprising a mixture of a first solvent component having a first chain transfer constant and a second solvent component having a second chain transfer constant, the second chain transfer constant being at least 5 times higher than the first chain transfer constant.

34. The method of any one of claims 1-7, comprising suspension polymerization.

35. The method of any one of claims 1-7, wherein polymerization occurs at a temperature greater than 0 ℃.

36. The method of any one of claims 1-7, wherein the polymer is hydrolyzed to form a hydrolyzed polymer having a degree of hydrolysis of at least 60 mol%.

37. The method of any one of claims 1-7, wherein the polymer has a UV absorption at 280nm that is at least 3 times greater than a UV absorption at 320 nm.

38. A branched polymer prepared according to the process of any preceding claim.

39. A branched polymer comprising (C ═ C) -C ═ O moieties at the ends of the chain, and having a UV absorbance at 280nm that is at least 3 times greater than the UV absorbance at 320nm, said polymer comprising the residues of:

(i) at least one monofunctional monomer having one polymerizable double bond per molecule;

(ii) at least one multifunctional monomer having at least two polymerizable double bonds per molecule; and

(iii) at least one chain transfer agent comprising an aldehyde or a ketone;

wherein the polymer has a degree of hydrolysis of at least 60 mol%.

40. The polymer of claim 39, comprising one or more residues of: one or more solvent components, at least one initiator, a second chain transfer agent, a second monofunctional monomer, and a second multifunctional monomer.

41. The polymer of claim 39 or 40, comprising 0.5 mol% and no greater than 45 mol% of a chain transfer agent comprising an aldehyde or ketone, based on the moles of residues of the monofunctional monomer.

42. A polymer according to claim 41, comprising ester groups, hydroxyl groups and optionally carboxylic acid groups.

43. According to any one of claims 39 to 40The polymer having at least 3,000 and not more than 1,000,000g.mol^-1Weight average molecular weight M of_w。

44. The polymer of any one of claims 39 to 40, having at least 1,500 and not greater than 500,000g.mol^-1Number average molecular weight M of_n。

45. The polymer of any one of claims 39 to 40 having a dispersity of at least 3 and not greater than 200 defined as M_w/M_n。

46. The polymer of claim 45 having a dispersity from 5 to 50.

47. The polymer of any one of claims 39 to 40, wherein a 4% w/w solution of the polymer has a viscosity of no greater than 50 mPa.s.

48. The polymer of any one of claims 39 to 40, wherein the intensity of the UV absorption peak at 280nm produced by a solution of the polymer is at least 4 times the intensity of the UV absorption peak at 320 nm.

49. The polymer of any one of claims 39 to 40, wherein the polymer comprises conjugated carboxylic acid groups derived from substituted or unsubstituted monofunctional monomers.

50. Use of a polymer according to any one of claims 39 to 49 in the suspension polymerisation of unsaturated monomers, wherein the polymer is used as a primary suspending agent.

51. A suspension polymerization composition comprising a continuous phase in which dispersed monomer beads are to be polymerized, and a polymer of any one of claims 39 to 49.